1. Field of the Invention:
The current invention relates to the building sector and particularly the surface coating sector, especially with regard to insulation using products, particularly insulants, made in situ from sprayed mineral fibres or particles and binders.
2. Background of the Prior Art:
It is known from French Pat. No. 2 442 807 corresponding to EP No. 11572 to insulate a backing by spraying onto it firstly an organic binder consisting of a filmogenic agent in colloidal solution in a solvent and then simultaneously on the one hand and through a first jet, some of the same organic binder as previously in colloidal solution and on the other, through a second jet, a mixture of particles, especially mineral fibres, and a powdered agent, especially borax, to coagulate the organic binder, and possibly pigments and fillers.
This technique is essentially used for the insulation of industrial premises, and when more particularly ceilings are involved, by reason of the action of gravity on the sprayed-on products, heterogeneity is observed in the thickness of the insulant obtained, migration of the binder and of possible colouring pigments in the thickness and their collection together on the surface, which results in the formation of a crust which is unpleasant to look at and also technically harmful, especially from the acoustic insulation and fire-resistance points of view.
These drawbacks are at least partly due to the fact that the binder, being distributed independently of the particles, fibres in particular, does not reach them all and therfore is not only non-uniformly distributed but is also unsatisfactorily retained by the said paticles or fibres.
Attempts have been made to reduce the quantity of binder sprayed on in order to reduce the risk of fire but in this case the mechanical properties of the resultant insulant are inadequate.
Further, the quantity of binder which is distributed with the particles, fibers in particular, depends on the settings made by the individual who does the projection.
These settings can be changed during the projection so that the projection of binder can be greatly increased for example to reinforce the adhesion on the backing, thus resulting in an increased risk of fire.
Furthermore, the excessive multiplicity of products which have to be conveyed onto a building site, and the risk of the binder freezing in water, constitute additional drawbacks.